Sensor device for measuring at least one property of a fluid medium

Abstract

A sensor device for measuring at least one property of a fluid medium, in particular of an exhaust gas of an internal combustion engine. The sensor device includes at least one protective housing for accommodating at least one sensor element; within the protective housing, at least one flow path being provided that allows flow therethrough by the fluid medium. The flow path has a number of at least three deflection points, where the fluid medium undergoes a directional change about an angle of at least 90°. The sensor device is highly resistant to thermal shock, while, at the same time, the sensor element has a high dynamic response.

What is claimed is: 
     
       1. A sensor device for measuring at least one property of a fluid medium, comprising:
 at least one protective housing for accommodating at least one sensor element, wherein within the protective housing, at least one flow path is provided that allows flow therethrough by the fluid medium, the flow path having at least three deflection points where the fluid medium undergoes a directional change about an angle of at least 90°; 
 wherein an inner housing surrounds the sensor element, the inner housing being at least partially surrounded by an outer housing, the outer housing surrounds the inner housing at least partially in a way that forms an intermediate space, the outer housing having at least one inlet opening for the fluid medium, the inner housing having at least one access opening for the fluid medium from the intermediate space, the flow path extending from the inlet opening across the intermediate space to the access opening; 
 wherein the outer housing is at least partially present in the form of a cylinder that is designed to include a curved surface area, the inlet opening being located in the curved surface area; 
 wherein the outer housing forms a hollow space into which the inner housing is introduced in a fixed form; 
 wherein a middle protective housing is positioned in the intermediate space between the outer housing and the inner housing, the flow path extends in the intermediate space through a region around the middle protective housing, and at least two of the deflection points is present in the region; and 
 wherein the middle protective housing is spaced from the inner housing so that the middle protective housing does not directly contact the inner housing. 
 
     
     
       2. The sensor device as recited in  claim 1 , wherein the fluid medium is an exhaust gas of an internal combustion engine. 
     
     
       3. The sensor device as recited in  claim 1 , wherein the number of deflection points in the flow path is at least four. 
     
     
       4. The sensor device as recited in  claim 3 , wherein the number of deflection points in the flow path is at least five. 
     
     
       5. The sensor device as recited in  claim 4 , wherein the number of deflection points in the flow path is at least six. 
     
     
       6. The sensor device as recited in  claim 1 , wherein the deflection points are adapted for precipitating liquid contained in the fluid medium from the fluid medium. 
     
     
       7. The sensor device as recited in  claim 1 , wherein the middle protective housing is configured in the intermediate space in a way that enables the fluid medium to accelerate on the flow path in the intermediate space. 
     
     
       8. The sensor device as recited in  claim 1 , wherein the middle protective housing has a turned over portion that projects into the intermediate space and has a remaining portion , the turned over portion having an angle of less than 180° relative to the remaining portion, and wherein the flow path is routed through a region adjacent to the angle, the region having at least two of the deflection points. 
     
     
       9. The sensor device as recited in  claim 8 , wherein the turned over portion has an angle of between 60° and 120° relative to the remaining portion. 
     
     
       10. The sensor device as recited in  claim 9 , wherein the turned over portion has an angle of 90°, relative to the remaining portion. 
     
     
       11. The sensor device as recited in  claim 1 , wherein the sensor element has a ceramic coating, in particular with a thermal shock coating. 
     
     
       12. The sensor device as recited in  claim 11 , wherein the ceramic coating is a thermal shock coating.